Umbrellas may be used to protect a user from the sun, wind or rain and may be portable or designed to be fixed to the ground (such as sun umbrellas having generally larger dimensions than portable rain umbrellas).
Fundamentally, the basic design of umbrellas has not changed in the past three centuries. Conventional umbrellas include a shaft to which a canopy is attached at one end and a handle is attached at the other end. A collapsible frame is included to support the canopy and which, when not in use, allows itself and the canopy to be lowered into a more compact state which may more easily be stored.
The collapsible frame consists of a number of ribs (usually eight ribs) evenly radially distributed about the shaft and pivotally connected at their inner ends to the canopy end of the shaft. The perimeter of the canopy is attached (often simply tied by threads) to the outer ends of each of the ribs. The end of each rib is generally exposed and provided with a stopper or other blunting device. In many umbrellas, in order to assist in raising/lowering the ribs and holding them in position, each rib is provided with a brace or strut which is pivotally connected at one of its ends to a point along the rib's length and at its other end it is pivotally connected to a slider which is slidable along the shaft. The slider is lockable in position near the canopy end of the shaft when in use.
Minor improvements have been made to the above described basic umbrella design for improved user convenience. Improvements include push-button self-erecting mechanisms usually incorporating a spring in which energy stored during collapsing of the umbrella is utilised to move the slider up the shaft to thereby erect the umbrella. Another relatively recent improvement is the provision of umbrellas which “fold down” to fit within a hand bag or briefcase for example. Umbrellas of this variety usually include a multi-segment shaft in which successive segments are a slide-fit within preceding segments. Further reductions in size are achieved by the use of multi-segmented canopy supporting ribs which are pivotally connected together and are collapsible in ‘V’ or ‘W’ shaped formations.
Problems with the above described conventional design (and its minor improvements) include the exposed rib ends which when in use, are positioned at or about eye level of passers-by and therefore pose a safety hazard. Also, in strong wind conditions the canopy may become detached from the frame while the frame has a tendency to turn inside-out, often resulting in irreparable damage to the umbrella frame and/or canopy.
It is also noted that in most if not all conventional umbrella designs, the canopy material is not optimally tensioned. This is because during erection of umbrellas having conventional frame designs, the vertical force provided by the user on the shaft slider is converted to compressive forces acting on the struts which in turn inefficiently convert the vertical force into a radially outwardly directed canopy tension. As the umbrella approaches its completely erect state, the struts (which support the ribs) approach the horizontal such that the majority of the effort being exerted by the user (the horizontal component of the strut force) is not being used while only a small proportion of the user's effort (the vertical component of the strut force) is usefully being employed in tensioning the canopy. This is readily observed when erecting conventional umbrellas in which resistance to shaft slider movement becomes increasingly apparent at the end of the slider's travel despite the rate of change of angle between rib and shaft reducing. Accordingly, in conventional umbrella designs, tension which could usefully be employed in the canopy is wasted in the ribs.
It would also be an advantage if an umbrella and/or umbrella frame could be developed in which the canopy could easily be replaced should it be desired or necessary.
It is therefore an object of the present invention to provide an umbrella and/or umbrella frame which will go at least some way towards overcoming the above disadvantages or addressing the above problems or which will at least provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.